1. Field of the Invention
The present invention relates to a block for use in constructing a retaining wall and a method for the construction of a retaining wall using the same.
2. Description of the Related Art
There is known a retaining wall block for use in constructing a retaining wall, which comprises a front wall and a partition wall formed backwards projecting from a rear surface of the front wall, the partition wall being formed with a communicating hole extending vertically over its entire length through and into which a reinforcing iron rod or rods is or are inserted and disposed.
When a retaining wall is to be constructed with the such retaining wall blocks, a plurality of the retaining wall blocks are laid in a row upwardly on a footing foundation so as to allow the communicating holes of the retaining wall blocks laid in the lower row to be aligned vertically with the communicating holes of the retaining wall blocks laid in an upper row.
More specifically, the footing foundation is formed integrally with a plurality of anchoring iron rods in a spaced arrangement so as to align with and extend upwardly through and in the communicating holes of the retaining wall blocks laid thereon and the reinforcing iron rods are disposed vertically so as to be inserted into and extend through the communicating holes of the retaining wall blocks laid on the footing foundation.
A plurality of the retaining wall blocks are laid in a row on the footing foundation so as to allow the communicating holes of the retaining wall blocks to align with the anchoring iron rods formed on the footing foundation and the reinforcing iron rods interconnected with the anchoring iron rods. After a row of the retaining wall blocks is laid on the footing foundation in the manner as described above, the communicating holes are filled with a filling and setting material such as concrete, mortar, etc. After the retaining wall blocks is laid in the lower row on the footing foundation and the communicating holes of the retaining wall blocks are filled with the filling and setting material, another plurality of the retaining wall blocks are laid in an upper row on the retaining wall blocks disposed in the lower row in the manner as described above and the communicating holes of the retaining wall blocks in the upper row were filled with the filling and setting material. A reinforced retaining wall can be constructed by repeating the laying of the retaining wall blocks in the manner as described above and the filling of the communicating holes with the filling and setting material until the retaining wall reaches a predetermined height.
A conventional retaining wall system using such retaining wall blocks poses various problems and difficulty.
The retaining wall system is required to withstand external forces such as, e.g. lateral shear forces because such lateral shear forces act upon a contact plane on which the adjacent retaining wall blocks constituting the retaining wall system contact with each other when an external force such as, for example, pressure of soil masses, works in a horizontal direction upon the retaining wall. In order to comply with this requirement, the conventional retaining wall system is constructed such that the number of interconnecting iron rods is increased. However, an increase in the number of the interconnecting iron rods leads to an increase in costs of construction and an prolongation of a construction period. Moreover, the retaining wall blocks cannot provide a retaining wall having a sufficiently high resistance to the lateral shear forces as compared with a retaining wall constructed by casting in place with concrete.
For iron-reinforced concrete constructions, as a general rule, it is desired to deal with the shear forces by increasing the strength of the concrete itself and any specification discloses this matter clearly. In the current situation, however, it is very difficult to build concrete constructions having a sufficient degree of physical strength as required by the specification.
Further, as a general rule, the front surface side of a retaining wall originally undergoes compressive forces under usual circumstances. In such an extreme case as in case of earthquake, etc., however, the front surface side of the retaining wall may undergo a tensile force caused by horizontal forces due to the horizontal seismic intensity in a way thoroughly opposite to the usual cases. At this instance, the iron-reinforced concrete construction may undergo upward or downward forces causing the retaining wall to slide vertically, i.e. upwardly or downwardly, whereby the retaining wall cannot function as an integral configuration and ensure a desired resistance force against the external forces.
Moreover, it is difficult to construct a retaining wall system in a rigid structure by laying a plurality of retaining wall blocks in plural rows one after another and increasing an amount of interconnecting iron rods for interconnecting the adjacent retaining wall blocks in such a manner that the retaining wall blocks laid adjacently and upwardly on each other are provided with resistance to vertical as well as longitudinal and lateral forces as comparable to a concrete retaining wall cast in place. Furthermore, the increase in the amount of the interconnecting iron rods lacks the economy of construction and increases the costs of construction.